There aren't any players like Ronaldo, not at Portugal, not at any other team in the world and this means Portugal will miss Ronaldo's contribution to the team without a doubt. With him, they had someone who could score easily, this dude is literally the highest goal scorer of all time, Pele and his family is making up numbers but Ronaldo is the highest scorer, while I do agree if Messi wants to keep going until after Ronaldo, because of the age gap, there is a possibility Messi could take that spot, right now Ronaldo is godly when he is playing and even at 40 years old he is great.
Portugal will not have someone like him, when he retires, he will not be replaced by anyone even remotely as good as him, and this will make Portugal a worse team for a long time until they find another talent maybe closer to him.
By the way, to my mind, World Cup means nothing for an athlete. If an athlete plays in a trush team, they can't win a World Cup because football is a game of 11 people, not 1. One person can't beat 11, even if he is the best.
I also don't like the idea of comparing Pele and his achievements to Ronaldo or Messi because football was very different during Pele's time. Football wasn't competitive sport as it is today. Now, footballers have to be top athletes with top talent to be competitive while years ago the bus driver was playing in club's defence